In this article by Jack Donovan the author of the book Mastering Oculus Rift Development explains about virtual reality. What made you feel like you were truly immersed in a game world for the first time? Was it graphics that looked impressively realistic, ambient noise that perfectly captured the environment and mood, or the way the game's mechanics just started to feel like a natural reflex? Game developers constantly strive to replicate scenarios that are as real and as emotionally impactful as possible, and they've never been as close as they are now with the advent of virtual reality.

Virtual reality has been a niche market since the early 1950s, often failing to evoke a meaningful sense of presence that the concept hinges on—that is, until the first Oculus Rift prototype was designed in 2010 by Oculus founder Palmer Luckey. The Oculus Rift proved that modern rendering and display technology was reaching a point that an immersive virtual reality could be achieved, and that's when the new era of VR development began.

Today, virtual reality development is as accessible as ever, comprehensively supported in the most popular off-the-shelf game development engines such as Unreal Engine and Unity 3D. In this article, you'll learn all of the essentials that go into a complete virtual reality experience, and master the techniques that will enable you to bring any idea you have into VR.

This article will cover everything you need to know to get started with virtual reality, including the following points:

• The concept of virtual reality
• The importance of intent in VR design
• Common limitations of VR games

(For more resources related to this topic, see here.)

The concept of virtual reality

Virtual reality has taken many forms and formats since its inception, but this article will be focused on modern virtual reality experienced with a Head-Mounted Display (HMD). HMDs like the Oculus Rift are typically treated like an extra screen attached to your computer (more on that later) but with some extra components that enable it to capture its own orientation (and position, in some cases). This essentially amounts to a screen that sits on your head and knows how it moves, so it can mirror your head movements in the VR experience and enable you to look around.

In the following example from the Oculus developer documentation, you can see how the HMD translates this rotational data into the game world:

Depth perception

Depth perception is another big principle of VR. Because the display of the HMD is always positioned right in front of the user's eyes, the rendered image is typically split into two images: one per eye, with each individual image rendered from the position of that eye.

You can observe the difference between normal rendering and VR rendering in the following two images. This first image is how normal 3D video games are rendered to a computer screen, created based on the position and direction of a virtual camera in the game world:

This next image shows how VR scenes are rendered, using a different virtual camera for each eye to create a stereoscopic depth effect:

Common limitations of VR games

While virtual reality provides the ability to immerse a player's senses like never before, it also creates some new, unique problems that must be addressed by responsible VR developers.

Locomotion sickness

Virtual reality headsets are meant to make you feel like you're somewhere else, and it only makes sense that you'd want to be able to explore that somewhere. Unfortunately, common game mechanics like traditional joystick locomotion are problematic for VR. Our inner ears and muscular system are accustomed to sensing inertia while we move from place to place, so if you were to push a joystick forward to walk in virtual reality, your body would get confused when it sensed that you're still in a chair.

Typically when there's a mismatch between what we're seeing and what we're feeling, our bodies assume that a nefarious poison or illness is at work, and they prepare to rid the body of the culprit; that's the motion sickness you feel when reading in a car, standing on a boat, and yes, moving in virtual reality. This doesn't mean that we have to prevent users from moving in VR, we just might want to be more clever about it—more on that later.

The primary cause of nausea with traditional joystick movement in VR is acceleration; your brain gets confused when picking up speed or slowing down, but not so much when it's moving at a constant rate (think of being stationary in a car that's moving at a constant speed). Rotation can get even more complicated, because rotating smoothly even at a constant speed causes nausea. Some developers get around this by using hard increments instead of gradual acceleration, such as rotating in 30 degree "snaps" once per second instead of rotating smoothly.

Lack of real-world vision

One of the potentially clumsiest aspects of virtual reality is getting your hands where they need to be without being able to see them. Whether you're using a gamepad, keyboard, or motion controller, you'll likely need to use your hands to interact with VR—which you can't see with an HMD sitting over your eyes. It's good practice to centralize input around resting positions (i.e. the buttons naturally closest to your thumbs on a gamepad or the home row of a computer keyboard), but shy away from anything that requires complex precise input, like writing sentences on a keyboard or hitting button combos on a controller.

Some VR headsets, such as the HTC Vive, have a forward-facing camera (sometimes called a passthrough camera) that users can choose to view in VR, enabling basic interaction with the real world without taking the headset off. The Oculus Rift doesn't feature a built-in camera, but you could still display the feed from an external camera on any surface in virtual reality.

Even before modern VR, developers were creating applications that overlay smart information over what a camera is seeing; that's called augmented reality (AR). Experiences that ride the line between camera output and virtual environments are called mixed reality (MR).

Unnatural head movements

You may not have thought about it before, but looking around in a traditional first-person shooter (FPS) is quite different than looking around using your head. The right analog stick is typically used to direct the camera and make adjustments as necessary, but in VR, players actually move their head instead of using their thumb to move their virtual head. Don't expect players in VR to be able to make the same snappy pivots and 180-degree turns on a dime that are trivial in a regular console game.

Summary

In this article, we approached the topic of virtual reality from a fundamental level. The HMD is the crux of modern VR simulation, and it uses motion tracking components as well as peripherals like the constellation system to create immersive experiences that transport the player into a virtual world.

Now that we've scratched the surface of the hardware, development techniques and use cases of virtual reality—particularly the Oculus Rift—you're probably beginning to think about what you'd like to create in virtual reality yourself

Resources for Article:

Further resources on this subject:

• Cardboard is Virtual Reality for Everyone [article]
• Virtually Everything for Everyone [article]
• Customizing the Player Character [article]